The present invention IMPROVED SELF-CLEANING FILTER refers to a series of improvements introduced into self-cleaning filters, for example filters for water cleaning, where the self-cleaning process is carried out by means of a temporary reversal in the direction of the water flow that intersects it.
The improvements for the invention have as an objective to minimize water consumption during this self-cleaning process, improving the cleaning conditions of the filtering disks, especially in the face of residuals of an adherent type, and facilitating their disassembly in the recurrent and indispensable manual deep cleaning operations.
The State of the Art, in what refers to self-cleaning filters, has undergone a rapid evolution in past times, fundamentally due to the development of its utilization in watering applications.
Known by the public in general is the advance reached in achieving a better usage of water resources, especially in regions characterized by a natural shortage of water. To this sense, we can cite as examples of this type of mentioned techniques, watering by sprinklers and watering by micro-spray. All of these modern techniques achieve a high degree of water usage. On the other hand, it is also obvious that more and more one turns to the use of poor quality waters, which frequently have impurities, and although these do not constitute an inconvenience in traditional watering techniques, they can be a serious problem in watering installations with sprinklers and micro-spray. For this reason, it is necessary to place filters, which prevent as much as possible the entry of impurities, brought by the water flow to the described watering installations with sprinklers and micro-spray.
The problem that arises then, with the usage of filters, is the one derived from the necessary cleaning and maintenance procedures associated to its operation, to eliminate the impurities accumulated in them.
With regards to this, self-cleaning filters have been known for some time, in which, starting from a cylindrical sensitive casing, placed inside the same are two coaxial chambers, a perimeter and an axial one, connected to each other through a plurality of filtering disks provided with grooves on their faces that are sometimes radial and sometimes oblique, so that when these disks are superimposed onto each other, the mentioned grooves become conduits of a reduced caliber, which are what confer to the device the filtering effect.
U.S. Pat. No. 4,707,259, describes a counter-current flow filter including a plurality of ring shaped filter elements placed one on top of the other forming an assembly of a generally cylindrical shape fastened to a cylinder, which are cleaned by counter current flow of a liquid through the mentioned elements. The filter includes a stopping mechanism to prevent the filter elements from vibrating during the filtration, but when the filter is being cleaned the stopping mechanism allows the filter elements vibration.
In European Patent EP0347477 a disk filter including a housing defining a fluid inlet and a fluid outlet is described. The filter element defines an upstream surface communication with the fluid inlet and a downstream surface communicating with the fluid outlet with a hollow volume interior limited by the disks that form the filter element.
In this type of filter, the encircling or external chamber is coupled to the corresponding water entry, generally radial, while the axial chamber is connected in turn to the flow exit for the filtered water, generally in an axial position, so that the water, conveniently pressurized, reaches the perimeter chamber in the first place, passes through the disks to reach the axial chamber, producing its filtering, and finally leaving the filter through the axial exist of the same.
Obviously the mentioned filtering conduits are damaged with dirt and with time, for which periodic cleanings of the same are necessary, for this reason it is also common to reverse the water flow direction, so that clean water enters through the flow exit, passing between the disks and carrying the dirt deposited in the same towards the usual entry mouth. Also known, to facilitate this maneuver, is that the disks be separated during the self-cleaning maneuver, to facilitate the detachment and carrying of the dirt.
This singularity makes these filters widely used, especially in countries where the cost of the manpower necessary for cleaning the filter is high, thereby those that are self-cleaning are preferred.
This structure brings an extensive and varied problem that centers mostly on the following aspects:
During the cleaning or self-cleaning phase an excessive consumption of water exists, for which the entire circulating flow, when reversed, becomes waste water.
In sewage waters and in those with a high degree of particles in suspension, the number of necessary cleanings is very high, and together with the waste of water in each cleaning, which is mentioned in the previous paragraph, makes the system very expensive.
The fixture rigidity of the mechanisms constituent of the filter to the corresponding support casing, hinders its disassembly when it is necessary to effect a manual deep cleaning, a maneuver that obviously must be repeated cyclically.
When the pollutants of the water to be filtered are of an adherent type, for example algae remains, the simple reversal of the flow causes an insufficient cleaning of the filtering disks, which forces shorter self-cleaning cycles, and more frequent manual deep cleaning operations.
For all of this, it is evident that the self-cleanings filters known in the State of the Art leave a considerable number of inconveniences without solving, for which improvements have been devised that make up the present improved self-cleaning filter that is described next.
With regards to the previously explained, the improvements that the invention proposes have been conceived in order to fully solve in a satisfactory manner the previously expressed problems, in their different commented areas.
Thereby, the present improved self-cleaning filter is composed of a basic structure, similar to other filters of this type, constituted by an external chamber, to which the water entry is coupled, in whose interior is located an axial chamber that communicates with the conduit or exit mouth, both chambers being defined by a framework of disks, found inside this external chamber, and the interior chamber is constituted by the interior of the disks or filtering rings.
One of the peculiar characteristics of the present self-cleaning filter is constituted by the support tower of the disks, that makes up the mentioned disk framework, whose end corresponding to the exit of clean water is completed by a seat base for a flap that acts as a stopper for the axial passage of the water, a flap that tends to act in a closing manner through a spring, conveniently impeded to allow opening the same during the normal flow of water when the filter acts as such, but automatically causing a closing action when the flow reversal takes place during the self-cleaning.
This flap is framed by a perimeter alignment of collectors, preferably in fours, that are not affected by the same and that establish the backward moving water flows during the self-cleaning phase, the collectors having for such a purpose orifices or windows for the exit of water specially directed towards the disks, allowing to cleanly select a small jet for each disk, with the object of achieving greater effectiveness in the self-cleaning phase of the water flow direction reversal.
This way, the water flow during the self-cleaning is considerably reduced with regards to the water flow under filtering conditions, this flow change automatically taking place in the flow reversal for cleaning.
In the same way, another singular characteristic of the present improved self-cleaning filter is constituted because the support tower of the filtering disks is completed in its end opposite the mentioned flap with a rammer that keeps the filtering disks conveniently separated during the filtering, this rammer being axially moveable against the tension of a spring, so that this mechanism pressing the disks, before an external action of any type, for example before a pneumatic pressure against the mentioned spring, allows the necessary separation between the filtering disks, to improve their cleaning, but all of this without producing a variation in the longitudinal dimension of the filtering element, which will be exactly the same in both the filtering phase and in the cleaning phase, which allows an easier coupling of the same to any casing type, since it does not require anything beyond the closing pressure of the latter to remain stable in its interior, allowing an extremely quick and simple extraction.
Besides the aforementioned, in the present improved self-cleaning filter it is provided that the orifices or windows of the self-cleaning collectors are adapted in a tilted position, so that the jets of water generated in each one impact obliquely on the disks, achieving two different and complementary effects, on the hand the elevation and consequent separation between the disks, and on the other the cleaning of the same, the first effect specifically due to the vertical component and the second to the horizontal component, tangential to the external surface of the filtering disks framework, to the force vector that sets the water flow.
It has also been provided that the windows be of a rectangular shape and that, considering the collectors in their entirety, they describe a helical path, which, on the one hand, contributes to the rising effect of the disks and, on the other, makes the cleaning water sweep the entire surface of the same.
The special incidence angle of the cleaning flows on each disk, also causes the rotation of the same, making the disks rotate freely removing the impurities and particles registered in the filtering process, which also contributes to improving the cleaning conditions.
Finally, and in accordance with another characteristic of the invention, it is provided that in the perimeter chamber defined on the outside of the disks, to which the water has access at first during the filtering phase, established, in the entry end will be helical deflectors that generate, due to the dynamic flow of water, a high turning speed of the same inside this chamber, that leads, by centrifugal force, to a displacement of the solid particles in suspension towards the casing wall, that is to say, to a lodging of the same with regards to the filtering block, which directly affects in an important way the time it takes to obstruct the filtering element, or what is the same, it makes the number of necessary cleanings lessen considerably, as these particles in suspension remain in the external limits of this chamber, without reaching the filtering rings.